Mosman’s coastal and marine environment is home to numerous species, including various sea birds, sea grasses, rays, octopus, sea horses and several species of fish.

Seagrasses

Seagrass beds grow in Harbour waters near Mosman providing habitat for a variety of marine life. Seagrass meadows also trap and stabilise sediments, helping to improve water clarity.

Seagrasses can be destroyed by stormwater run-off carrying excess nutrients and sediments as well as by anchor chains, boat propellers, discarded fishing lines, construction of jetties and seawalls, dredging and land reclamation. Such pressures have contributed to a decline in seagrass populations near urban areas.

Sea grass beds are important habitats protected by legislation so if boating be especially careful to avoid damaging them when anchoring.

Seahorses

Waters surrounding Mosman are home to over 500 tiny seahorses from two species, White’s Seahorse (Hippocampus whitei) and Big Belly Seahorse (Hippocampus abdominalis).

Big Belly Seahorse is also found in New Zealand, while White’s seahorse is endemic to (only found in) Australia.

The seahorses grow to around 18-20cm long and live amongst seagrass and algae beds. They are almost invisible in the small clumps of marine vegetation as they are very well camouflaged in murky shades of mottled yellow, orange, brown, grey and black.

Fortunately they are protected under NSW legislation. It is illegal to harm or move seahorses in NSW, and many are under close surveillance. Scientists and SCUBA divers are monitoring the numbers of seahorses at Mosman and at Manly.

Our whale friend Gamarada and her calves are at risk from numerous threats.

Whales and Threats to Whales

Five whale species, the humpback, blue, fin, sei and southern right, have been listed as threatened species by the Australian Government. Recovery Plans have been created for these species. The Recovery Plan outlines the threats to the species and actions required to halt the decease in the number of the species.

Threats to whales include marine pollution such as plastic bags, fishing nets and line and cigarette butts. Whales, as well as seals, turtles and sea birds can mistake plastic waste for food or become entangled in it causing pain and death. In every square mile of ocean it is estimated that there are over 46,000 pieces of plastic. Litter is washed into the sea from waterways or blown from the land, so it is important to dispose of rubbish appropriately so that it does not end up in the ocean killing marine life.

Fishing nets can become lost at sea, floating through the oceans for years continually trapping and killing marine animals such as dolphins and dugongs. These nets are often referred to as ghost nets. Meanwhile overfishing and illegal fishing depletes the ocean of fish stocks in the food webs of marine ecosystems.

Whaling is of particular concern to many due to the inhumane practices that inflict cruelty upon whales and the fact that whaling is unnecessarily threatening whale populations. Australia stoppped whaling in 1979 and has since sought a permanent ban on commercial and ‘scientific’ whaling. As whales are migratory species, their protection requires international cooperation. The Australia Government aims to achieve whale conservation through the International Whaling Commission (IWC). Click here for a fact sheet on the IWC. For more information go to the Australian Government Department of the Environment .

What You Can Do

Reduce, reuse and recycle, and dispose of rubbish appropriately so that it does not enter the ocean.

Sharks

SharkSmart offers advice on how to reduce the risk of shark attack and aims to inform the public about sharks, their habitat and nature.

Sharks are a natural part of healthy oceanic and estuarine environments. When people enter open water, they are entering the shark’s domain. A better awareness and understanding of sharks and their behaviour can help those who wish to enjoy the world class waterways of New South Wales.

Australia’s Marine Ecology

Australia’s stunning coastlines are the envy of the world with over 3 million international visitors a year.

Australian waters contain:

43 different species of whales, porpoises and dolphins

Over 4 000 fish species – 20% of all species recorded worldwide

Giant kelp forests up to 30 metres high!

80 to 90% of our marine species are not found anywhere else in the world!

Biological material from the ocean is used for numerous benefits, including pharmaceuticals. In addition to marine biotechnology, other marine based industries may also develop further such as alternative energy sources.